In fiber optical systems there are at different points required optical connections between the different optical elements included in the system. Thus, there are required optical connections between different lengths of optical fibers, between an optical fiber and a light source, for example a diode, between an optical fiber and a light detector. Each connection must be established using very great accuracy if the losses shall be kept at a minimum. Of course, the problem of providing a correct connection is caused by the fact that optical fibers have a very small cross sectional area and also because small deviations from a correct position between two fiber end portions to be connected with each other cause substantial losses. It is important especially to avoid angular deviations between the fibers, i.e. it is important that the fibers connected with each other are positioned on the same optical axis.
Different devices for providing a correct connection of optical fibers with each other and with other optical elements have been suggested. Such devices comprise lens systems in which the light beam is magnified so that the light transmission in the connection takes place at a sectional area which is magnified several times providing for a corresponding reduction of the sensitivity to deviations from the correct position. Thereby, it is a drawback that the connection of two fiber end portions to each other requires instead of one single connection, i.e. the connection between the fiber end portions, an optical connection of the fiber end portions, each to one lens, and an optical connection between the lenses, i.e. three connections. It is important that the optical fibers and the lenses are positioned on the same optical axis as well as that the end surfaces of the fibers are positioned in the focus of the lens in question. Thus, the connections between the optical fibers and the lenses are the most sensitive parts of the connection system while the optical connection of the lenses to each other can easily be provided without errors.
Different devices for connecting an optical element with a lens are previously known. A drawback of previously known connection devices is that they are either complicated in their construction or use or offer insufficient accuracy with regard to the fact that the optical element and the lens shall be positioned on the same optical axis and that the optical element shall be positioned in the focus of the lense.